The present invention relates to adapters for hydraulic hoses and tubes, particularly those used in high pressure environments. More particularly, the present invention is concerned with a hydraulic hose adapter, for attaching a threaded coupling to a hose or tubing, which uses an 0-ring and a stop for improving the fluid seal.
U.S. Pat. No. 4,458,926 discloses a hydraulic hose adapter, and is hereby explicitly incorporated by reference herein. The hose coupling, known as a "Flare-0" fitting, includes centrally bored male and female members and an internally threaded sleeve. The female member rotatably receives the male member, which is engaged by the sleeve. The female and male members are provided with smooth, frustoconical, metal female and male seating surfaces, respectively. The male seating surface is interrupted by a circular groove. The cross sectional area of the groove is greater than that of the 0-ring. The 0-ring is made of deformable but noncompressible material, and the groove is positioned so that the female seating surface contacts the male seating surface on each side of the groove.
A problem with this prior art fitting involves "nose collapse". "Nose collapse" occurs when the male taper seat is driven down, under heavy torque, inside the taper of the female component. The collapse of the nose of a male fitting is directly related to the amount of the linear travel of the male component once engaged with the female tapered surface. The reduction in diameter is related to linear distance traveled as a function of the angle of the taper, conventionally 37.degree. or 45.degree. . With the 37.degree. fittings, the nose collapse is 1.5071 of the diameter for each 1.0 of linear travel. Therefore, if an installer tightens the fitting by 0.030" in a linear direction, the bore diameter would be reduced by approximately 0.045", which is a significant reduction on smaller sizes of fittings. A deformed nose does not necessarily cause malfunctions within the fitting, but the deformation is not a desired feature.
One method of avoiding the nose collapse problem is to remove the leading portion of the nose ahead of the 0-ring, but such a reduction would reduce the functionality of the fitting. What is needed in the art is a fitting of the type described above which overcomes the problem of nose collapse without impairing the functionality of the coupling.